Packet streaming technology is one of the conventional methods for delivering moving-image content via communication lines. Streaming is a method of playing back content data, of which a content provider server holds, by means of a playback program installed on a user computer while downloading the content data. There is another providing method, in which a playback program plays back content data after all the blocks of content data are once downloaded to a hard disk drive provided on a user computer. In order to play back the downloaded content data on a device other than that computer, the user needs to copy the content data, which is downloaded on the hard disk drive of the computer, to a storage medium such as a DVD (hereinafter referred to as a removable medium). The content data copied on the removable medium can be played back on another computer, a DVD player, etc.